Vehicles, such as automobiles and trucks for example, include a differential housing and axle assembly, sometime colloquially referred to as a drive module. The drive module is connected to the vehicle engine by a prop-shaft. The prop-shaft transmits rotational energy (torque) developed by the vehicle engine to the assembly, which in turn transmits the rotational energy to the wheels. In a rear-wheel drive vehicle, the prop-shaft directly couples the assembly to the vehicle's transmission. In an all-wheel or four-wheel drive vehicle, additional components may also be included, such as a power take-off unit for example.
It should be appreciated that the rotation of the gears within the drive module may generate or transmit vibrations. These vibrations may in some instances become a noise source that may be transmitted to the vehicle compartment. Testing equipment and methods have been developed to allow the measurement of NVH prior to installation in the vehicle. The NVH testing methods typically involve connecting an energy source (e.g. a motor) to the pinion shaft entering the differential housing and at each wheel. Alignment of the rotating shafts needs to be accomplished within desired specifications otherwise inconsistent test results may occur. It has been found that alignment of the shafts and clamping of the drive module to the test fixture are large contributors to NVH tester repeatability and throughput issues.
Accordingly, it is desirable to provide a drive module that facilitates NVH testing with a desired level of reliability.